1. Field of the Invention
This invention relates to an image projecting system for projecting an image on a microfilm on a magnified scale on an image receiver. More particularly, this invention relates to an image projecting system intended for use as an image projector for a reader or a reader printer, for example, and provided with a masking device for masking the area of an image on microfilm other than a desired area thereof and allowing only the desired part of the image to be projected on an image receiver.
2. Description of the Prior Art
A reader is used for projecting on a screen a desired image selected from all the images recorded on a microfilm. A reader printer is provided with a screen for the projecting thereon of a desired image selected from all the images recorded on the microfilm and a copying unit for printing the image. The image projecting system of this class incorporates in the optical path thereof a masking device for the purpose of enabling only a desired part of the images recorded on the microfilm to be projected on the screen for close inspection and, at the same time, to be copied.
Japanese Utility Model Publication SHO 55(1980)-18,817 discloses an image projecting system which is provided with a masking plate for the purpose of enabling a desired area of an image selected from the images recorded on a microfiche film to projected on a screen and keeping the area of the image other than the desired area masked. Owing to the use of this masking plate, the masked area of the image is displayed undecipherably on the screen or the area not masked and the masked area are displayed as distinguished from each other on the screen.
Japanese Utility Model Laid-Open SHO 61(1986)-104,443 discloses a copying machine which is provided beneath an original stand with a sheet-like light shielding member having formed therein openings of a plurality of sizes matched to varying sizes of originals. Owing to this construction, the particular one of the openings having a size conforming to the size of a given original is positioned correspondingly to the original so that the light is enabled to pass through the opening and impinge on the original. The conventional techniques of this principle are incapable of tilting the masking area.
Another problem is that images can be recorded as tilted in a microfilm. When this type of microfilm is loaded in a carrier unit and the images under discussion are projected on the screen, these images are displayed in a slanted state. If a microfilm on which such images have been recorded are held in a correct position in the carrier unit, the projected images appear in a tilted state. If the images in this state are copied, then the copied images present a slanted appearance.